RAFT polymerisation, as described in International Patent Publication Nos. WO 98/01478, WO 99/31144 and WO 10/83569, is a polymerisation technique that exhibits characteristics associated with living polymerisation. Living polymerisation is generally considered in the art to be a form of chain polymerisation in which irreversible chain termination is substantially absent. An important feature of living polymerisation is that polymer chains will continue to grow while monomer and the reaction conditions to support polymerisation are provided. Polymers prepared by RAFT polymerisation can advantageously exhibit a well defined molecular architecture, a predetermined molecular weight and a narrow molecular weight distribution or low polydispersity.
RAFT polymerisation is believed to proceed under the control of a RAFT agent according to a mechanism which is simplistically illustrated below in Scheme 1.

With reference to Scheme 1, R represents a group that functions as a free radical leaving group under the polymerisation conditions employed and yet, as a free radical leaving group, retains the ability to reinitiate polymerisation. Z represents a group that functions to convey a suitable reactivity to the C═S moiety in the RAFT agent towards free radical addition without slowing the rate of fragmentation of the RAFT-adduct radical to the extent that polymerisation is unduly retarded.
RAFT polymerisation is one of the most versatile methods of controlled radical polymerisation at least in part because of its ability to be performed using a vast array of monomers and solvents, including aqueous solutions.
Despite the advantages afforded by RAFT polymerisation, there has been limited research and development to date into processes for preparing commercial scale quantities of so called RAFT polymer (i.e. polymer formed by RAFT polymerisation). Accordingly, there remains an opportunity to develop a process for producing RAFT polymer in commercial quantities, or to at least to develop a useful alternative process for preparing RAFT polymer compared with state of the art processes.